纳米碳酸锌的制备和热分解动力学参数的测定

Nanosized zinc carbonate was prepared in the droplet of nano-reactor based on microemusion. The influences of the concentration of the surfactant and reactant on the diameter of nanoparticles were studied and the kinetic pa-rameters of thermal decomposition reaction were determined. It can be shown from experimental results， the di-ameter of the droplet in the microemulsion which have dissolved reactant zinc nitrate and sal volatile is between 4.9nm and 7.7nm， 6.2nm and 12.4nm， respectively. Nanosized zinc carbonate prepared by the method of mi-croemusion has shown good dispersion， narrow distribution and light agglomeration. The particle size of nanosized zinc carbonate is between 5nm and 40nm， and its kinetic parameters of thermal decomposition reaction-activation energy E and reaction order n are 110kJ·mol^-1 and 0.9， respectively.     

ZSM-5分子筛酸位分布及其甲醇制烯烃催化性能的定向管理与调控

ZSM-5分子筛在甲醇制烯烃(MTO)过程中的催化性能和反应机理与其孔道中酸位点分布位置紧密相关. 本文证明在水热合成过程中加入适量的钠离子(Na⁺)可以增加ZSM-5分子筛交叉腔酸位点比例; 从而促进高级甲基苯的生成并加速芳烃循环, 有利于乙烯生成. 相反, 在合成过程中不添加钠离子, 所制备的ZSM-5分子筛直孔道和正弦孔道酸位点比例明显提高, 有利于促进烯烃循环并提高丙烯和C₃₊烯烃选择性.     

RUB-13分子筛的合成及其甲醇制烯烃催化性能

采用水热法合成RUB-13分子筛,探讨了有机模板剂(OSDA)、硅源、晶化温度和水硅比等制备条件对RUB-13分子筛晶体结构的影响,考察了RUB-13分子筛在甲醇制烯烃(MTO)反应中的催化性能。结果表明,采用1,2,2,6,6-五甲基哌啶(PMP)为有机模板剂、白炭黑为硅源,在晶化温度为170℃的条件下,选择H2O/Si比为100和80时可分别合成出高纯度的低硅铝比(Si/Al=100)和高硅铝比(Si/Al=200)的RUB-13分子筛晶体,且晶粒呈棒状形貌。H-Al-B-RUB-13(Si/Al=200)分子筛用于催化甲醇制烯烃反应时,在400℃下表现出高的低碳烯烃选择性(C2=-5选择性达97. 8%,丙烯选择性为54. 5%),优于传统的H-SAPO-34和H-ZSM-5分子筛催化剂。     

SiO_2气凝胶负载磷钨酸催化四氢呋喃聚合反应的研究

采用等体积浸渍法制备了SiO2气凝胶负载磷钨酸(HPW)催化剂,利用BET、XRD、NH3-TPD、FT-IR、Py-IR对催化剂结构及表面性质进行了表征.将催化剂应用于四氢呋喃(THF)聚合反应,考察了HPW负载量、聚合时间、聚合温度等条件的影响.结果表明:在负载量50%,反应温度50℃、反应时间4 h条件下,反应收率达53%,聚合物数均分子量2000左右,可用作纺织、化工等领域的生产原料.     

Effect of N2 Plasma Annealing of Properties of Fluoring Doped Silicon Dioxide Films with Low Dielectric Constant for Ultra—Large—Scale Integrated Circuits

The influence of N2 plasma annealing on the properties of fluorine doped silicon oxide (SiOF) films is investigated.The stability of the Dielectric constant of SiOF film is remarkably improved by the N2 plasma annealing.After enduring a moisture absorption test for six hours in a chamber with 60% humidity at 50℃,the dielectric constant variation of the annealed SiOF films is only 1.5%,while the variation for those SiOF films without annealing is 15.5%.Fourier transform infrared spectroscopic results show that the absorption peaks of Si-OH and H-OH of SiOF films are reduced after the N2 plasma annealing because the annealing can wipe off some unstable Si-F2 bonds in SiOF films.These Unstable Si-F2 bonds are suitable to react with water,resulting in the degradation of SiOF film properties.Therefore,the N2 plasma annealing meliorates the properties of SiOF films with low dielectric constant.     

An accurate measurement of PMT TTS based on the photoelectron spectrum

The water Cherenkov detector array (WCDA) for the Large High Altitude Air Shower Observatory (LHAASO) will employ more than 3600 hemisphere 8-inch photomultiplier tubes (PMTs). Good time performance of the PMT, especially the transit time spread (TTS), is required for the WCDA. In order to meet the demand of the WCDA experiment, an accurate measurement of PMT TTS based on the photoelectron spectrum is studied. The method is appropriate for multi-photoelectrons and makes it possible to measure the TTS of different photoelectrons simultaneously. The TTS of different photoelectrons for a Hamamatsu R5912 PMT is tested with a specially designed divider circuit. The relationship between TTS and number of photoelectrons is also presented in this paper.     

两步晶化法合成纳米SAPO-34分子筛及其催化性能

分别以拟薄水铝石、硅溶胶和磷酸为铝源、硅源和磷源,四乙基氢氧化铵为模板剂,采用两步水热晶化法合成出粒径为200～300 nm的纳米级SAPO-34分子筛.采用X射线衍射(XRD)、X射线荧光光谱(XRF)、29Si 、27Al、31P MAS NMR、SEM、BET和NH3-TPD等手段对合成的SAPO-34分子筛进行...     

正方形排列棒束元件中压力对临界热流密度影响的实验研究

一、前言 近三十年来,各国对临界热流密度(CHF)进行了一系列的研究,企图推导出理论关系式来计算反应堆燃料组件的CHF值。但是至今仍未取得满意的结果。目前用于反应堆热工设计的CHF关系式仍然是一些经验关系式。为了得到特定结构压水堆燃料组     

紫外氟磷玻璃的高能激光损伤研究进展

激光驱动惯性约束聚变(ICF),因有望解决全球能源危机问题而备受瞩目。然而,熔石英作为ICF装置终端光学组件中一类重要的功能性紫外元件,其高能激光诱导损伤问题成为限制ICF装置输出能量向更高更强方向发展的关键因素。因此,ICF装置负载能力继续提升对新型高抗强激光损伤紫外元件提出重大应用需求。综述了中国科学院西安光学精密机械研究所研制的紫外氟磷玻璃在高能紫外激光损伤方面的研究现状,并分析了现存的实际问题,最后对高抗损伤紫外氟磷玻璃的发展方向进行了展望。     

新型复合正极材料5LiMn0.9Fe0.1PO4·Li3V2(PO4)3/C的制备及电化学性能研究

用固相法制备了5LiMn0.9Fe0.1PO4·Li3V2(PO4)3/C复合正极材料.采用XRD、SEM、TEM和电化学测试等对材料进行了表征.结果表明,复合材料由LiMn0.9Fe0.1PO4和Li3V2(PO4)3两相组成,不含其它杂质.Li3V2(PO4)3的加入使得LiMn0.9Fe0.1PO4的电化学性能得到极大地提高.该复合材料在0.05 C和1C倍率下的放电比容量分别为162.8 mAh·g-1和129.6mAh·g-1,在1C倍率下循环50次后的容量保持率为90.1;.